Lens element

ABSTRACT

A lens element intended to be worn in front of an eye of a person includes a prescription portion having a first refractive power based on a prescription for correcting an abnormal refraction of the eye of the person and a second refractive power different from the first refractive power. The lens element further includes a plurality of at least three optical elements, at least one optical element having an optical function of not focusing an image on the retina of the eye to slow down the progression of the abnormal refraction of the eye.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of and claims thebenefit of priority of U.S. application Ser. No. 16/976,595, filed Aug.28, 2020, which is a national stage application of PCT Application No:PCT/EP2019/055220, filed Mar. 1, 2019, which claims priority to EuropeanPatent Application Nos. 18305216.6, filed Mar. 1, 2018; 18305217.4,filed Mar. 1, 2018; 18305384.2, filed Mar. 30, 2018; 18305385.9, filedMar. 30, 2018; 18305435.2, filed Apr. 11, 2018; 18305436.0, filed Apr.11, 2018; 18305526.8, filed Apr. 26, 2018; and 18305527.6, filed Apr.26, 2018, the entire contents of which is incorporated herein byreference.

TECHNICAL FIELD

The invention relates to a lens element intended to be worn in front ofan eye of a person to suppress progression of abnormal refractions ofthe eye such as myopia or hyperopia.

BACKGROUND OF THE INVENTION

Myopia of an eye is characterized by the fact that the eye focusesdistant objects in front of its retina. Myopia is usually correctedusing a concave lens and hyperopia is usually corrected using a convexlens.

It has been observed that some individuals when corrected usingconventional single vision optical lenses, in particular children, focusinaccurately when they observe an object which is situated at a shortdistance away, that is to say, in near vision conditions. Because ofthis focusing defect on the part of a myopic child which is correctedfor his far vision, the image of an object close by is also formedbehind his retina, even in the foveal area.

Such focusing defect may have an impact on the progression of myopia ofsuch individuals. One may observe that for most of said individual themyopia defect tends to increase over time.

Foveal vision corresponds to viewing conditions for which the image ofan object looked at is formed by the eye in the central zone of theretina, called the foveal zone.

Peripheral vision corresponds to the perception of elements of a scenethat are offset laterally relative to the object looked at, the imagesof said elements being formed on the peripheral area of the retina, awayfrom the foveal zone.

The ophthalmic correction with which an ametropic subject is provided isusually adapted for his foveal vision. However, as is known, thecorrection has to be reduced for the peripheral vision relative to thecorrection that is determined for the foveal vision. In particular,studies carried out on monkeys have shown that strong defocusing of thelight behind the retina, which occurs away from the foveal zone, maycause the retina of the eye to extend and therefore may cause a myopiadefect to increase.

Therefore, it appears that there is a need for a lens element that wouldsuppress or at least slow down progression of abnormal refractions ofthe eye such as myopia or hyperopia.

SUMMARY OF THE INVENTION

To this end, the invention proposes a lens element intended to be wornin front of an eye of a wearer, in standard wearing conditions, the lenselement comprising:

-   -   a prescription portion configured to provide to the wearer for        foveal vision a first optical power based on the prescription of        the wearer for correcting an abnormal refraction of said eye of        the wearer;    -   a plurality of at least three optical elements, at least one        optical element having an optical function of not focusing an        image on the retina of the eye for peripheral vision so as to        slow down the progression of the abnormal refraction of the eye.

Advantageously, having optical elements that are configured to not focusan image on the retina of the wearer for peripheral vision reduce thenatural tendency of the retina of the eye to deform, in particular toextend. Therefore, the progression of the abnormal refraction of the eyeis slow down.

According to further embodiments which can be considered alone or incombination:

-   -   at least one, for example all, of the optical element has an        optical function of focusing an image on a position other than        the retina in standard wearing conditions and for peripheral        vision; and/or    -   at least one optical element has a non-spherical focused optical        function in standard wearing conditions and for peripheral        vision; and/or    -   at least one of the optical elements has a cylindrical power;        and/or    -   the optical elements are configured so that along at least one        section of the lens the mean sphere of optical elements        increases from a point of said section towards the peripheral        part of said section; and/or    -   the optical elements are configured so that along at least one        section of the lens the cylinder of optical elements increases        from a point of said section towards the peripheral part of said        section; and/or    -   the optical elements are configured so that along the at least        one section of the lens the mean sphere and/or the cylinder of        optical elements increases from the center of said section        towards the peripheral part of said section; and/or    -   the prescription portion comprises an optical center and the        optical elements are configured so that along any section        passing through the optical center of the lens the mean sphere        and/or the cylinder of the optical elements increases from the        optical center towards the peripheral part of the lens; and/or    -   the prescription portion comprises a far vision reference point,        a near vision reference, and a meridian joining the far and near        vision reference points, the optical elements are configured so        that in standard wearing conditions along any horizontal section        of the lens the mean sphere and/or the mean cylinder of the        optical elements increases from the intersection of said        horizontal section with the meridian towards the peripheral part        of the lens; and/or    -   the mean sphere and/or the cylinder increase function along the        sections are different depending on the position of said section        along the meridian; and/or    -   the mean sphere and/or the cylinder increase function along the        sections are unsymmetrical; and/or    -   the optical elements are configured so that in standard wearing        condition the at least one section is a horizontal section;        and/or    -   the mean sphere and/or the cylinder of optical elements        increases from a first point of said section towards the        peripheral part of said section and decreases from a second        point of said section towards the peripheral part of said        section, the second point being closer to the peripheral part of        said section than the first point; and/or    -   the mean sphere and/or the cylinder increase function along the        at least one section is a Gaussian function; and/or    -   the mean sphere and/or the cylinder increase function along the        at least one section is a Quadratic function; and/or    -   the optical elements are configured so that the mean focus of        the light rays passing through each optical element is at a same        distance to the retina; and/or    -   the prescription portion is formed as the portion other than the        portions formed as the plurality of optical elements; and/or    -   for every circular zone having a radius comprised between 2 and        4 mm comprising a geometrical center located at a distance of        the framing reference that faces the pupil of the user gazing        straight ahead in standard wearing conditions greater or equal        to said radius+5 mm, the ratio between the sum of areas of the        parts of optical elements located inside said circular zone and        the area of said circular zone is comprised between 20% and 70%;        and/or    -   the at least three optical elements are non-contiguous; and/or    -   at least part, for example all, of the optical elements are        located on the front surface of the ophthalmic lens; and/or    -   at least part, for example all, of the optical elements are        located on the back surface of the ophthalmic lens; and/or    -   at least part, for example all, of the optical elements are        located between the front and the back surfaces of the        ophthalmic lens; and/or    -   at least one of the optical elements is a multifocal refractive        micro-lens; and/or    -   the at least one multifocal refractive micro-lens comprises an        aspherical surface, with or without any rotational symmetry;        and/or    -   at least one of the optical elements is a toric refractive        micro-lens; and/or    -   the at least one multifocal refractive micro-lens comprises a        toric surface; and/or    -   the at least one multifocal refractive micro-lens has a        cylindrical power; and/or    -   at least one of the optical elements is made of a birefringent        material; and/or    -   at least one of the optical elements is a diffractive lens;        and/or    -   the at least one diffractive lens comprises a metasurface        structure; and/or    -   at least one optical elements has a shape configured so as to        create a caustic in front of the retina of the eye of the        person; and/or    -   at least one optical element is a multifocal binary component;        and/or    -   at least one optical element is a pixelated lens; and/or    -   at least one optical element is a it-Fresnel lens; and/or    -   at least part, for example all, optical functions comprise high        order optical aberrations; and/or    -   the lens element comprises an ophthalmic lens bearing the        prescription portion and a clip-on bearing the optical elements        adapted to be removably attached to the ophthalmic lens when the        lens element is worn; and/or    -   the optical elements have a contour shape being inscribable in a        circle having a diameter greater than or equal to 0.8 mm and        smaller than or equal to 3.0 mm; and/or    -   the prescription portion is further configured to provide to the        wearer in standard wearing conditions and for foveal vision a        second optical power different from the first optical power;        and/or    -   the difference between the first optical power and the second        optical power is greater than or equal to 0.5D; and/or    -   at least one, for example at least 70%, for example all optical        elements are active optical element that may be activated by an        optical lens controller device; and/or    -   the active optical element comprises a material having a        variable refractive index whose value is controlled by the        optical lens controller device, and/or    -   the optical elements are positioned on a network; and/or    -   the network is a structured network; and/or    -   the structured network is a squared network or a hexagonal        network or a triangle network or an octagonal network; and/or    -   the lens element further comprises at least four optical        elements organized in at least two groups of optical elements;        and/or    -   each group of optical element is organized in at least two        concentric rings having the same center, the concentric ring of        each group of optical element being defined by an inner diameter        corresponding to the smallest circle that is tangent to at least        one optical element of said group and an outer diameter        corresponding to the largest circle that is tangent to at least        one optical elements of said group; and/or    -   at least part of, for example all the concentric rings of        optical elements are centered on the optical center of the        surface of the lens element on which said optical elements are        disposed; and/or    -   the concentric rings of optical elements have a diameter        comprised between 9.0 mm and 60 mm; and/or    -   the distance between two successive concentric rings of optical        elements is greater than or equal to 5.0 mm, the distance        between two successive concentric rings being defined by the        difference between the inner diameter of a first concentric ring        and the outer diameter of a second concentric ring, the second        concentric ring being closer to the periphery of the lens        element.

The invention further relates to a method for determining a lens elementadapted to slow down the progression of the abnormal refraction of theeye of a wearer, the method comprising:

-   -   a wearer prescription data providing step, during which wearer        prescription data relating the prescription of the wearer are        provided,    -   a wearing condition data providing step, during which wearing        condition data relating to wearing conditions of the lens        element by the wearer,    -   a wearer retina data providing step during which wearer retina        data relating to the shape of the retina of the wearer in the        same reference frame as the wearing conditions are provided,    -   a lens element determining step during which a lens element        comprising a prescription portion and a plurality of at least        three optical elements is determined so that the prescription        portion provides in wearing conditions corresponding to the        wearing data and for foveal vision a first optical power based        on the prescription of the wearer and at least one optical        element has an optical function of not focusing an image on the        retina of the eye for peripheral vision.

Advantageously, the method of the invention allows controlling therefraction of the light in peripheral vision through the opticalelements using ray tracing. Therefore, one can decide to have theoptical elements so as to focus light rays before the retina of thewearer or so as not to focus the light rays. One may consider standardor customized conditions, such as wearing conditions or the shape of theretina.

Furthermore, the method of the invention allows controlling the averagefocusing or point or min and max range by optical element at a certaindistance from the retina in specific wearing condition and taking intoaccount the retina of the wearer and depending on the eccentricity.

For example, for a spherical optical element the method of the inventionallows determining the peripheral astigmatic image whose best focus isat 2 D of the retina.

For example, for a toric optical element the method of the inventionallows determining the peripheral point image whose best focus isconstant by 3 D whatever the position of the optical element.

According to further embodiments which can be considered alone or incombination:

-   -   during the lens element determining step at least 50%, for        example at least 80%, of the optical elements are determined so        as to focus an image at a given distance of the retina; and/or    -   during the lens element determining step at least 50%, for        example at least 80%, of the optical elements are determined so        as to focus an image at a same distance of the retina along the        axis linking a reference point of each optical element and the        center of the pupil of the wearer; and/or    -   the wearing condition data provided during the wearing condition        data providing step correspond to standard wearing conditions;        and/or    -   the wearing condition data provided during the wearing condition        data providing step correspond to wearing conditions measured on        the wearer; and/or    -   the wearer retina data provided during the wearer retina data        providing step correspond to standard retina shape; and/or    -   the wearer retina data provided during the wearer retina data        providing step correspond to the shape of the retina measured on        the wearer; and/or    -   the method further comprises a front surface data providing step        during which front surface data representative of the front        surface of the lens element are provided, and wherein during the        lens element determining step the shape of the back surface and        the optical elements to be placed on the front surface are        determined so that the prescription portion provides in wearing        conditions corresponding to the wearing data and for foveal        vision a first optical power based on the prescription of the        wearer and at least one optical element has an optical function        of not focusing an image on the retina of the eye for peripheral        vision.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the invention will now be described withreference to the accompanying drawing wherein:

FIG. 1 is a plan view of a lens element according to the invention;

FIG. 2 is a general profile view of a lens element according to theinvention;

FIG. 3 represents an example of a Fresnel height profile;

FIG. 4 represents an example of a diffractive lens radial profile;

FIG. 5 illustrates a it-Fresnel lens profile;

FIGS. 6a to 6c illustrate a binary lens embodiment of the invention;

FIG. 7a illustrates the astigmatism axis γ of a lens in the TABOconvention;

FIG. 7b illustrates the cylinder axis γ_(AX) in a convention used tocharacterize an aspherical surface;

FIGS. 8 to 10 a show, diagrammatically, optical systems of eye and lens;

FIG. 10b illustrates oblique astigmatism;

FIG. 11 is a flowchart of a method according to the invention.

FIG. 12 is a plan view of a lens element according to an embodiment ofthe invention;

FIGS. 13 to 17 illustrate different organizations of optical elementsaccording to different embodiments of the invention; and

FIGS. 18a to 19b illustrate different types of junction between opticalelements according to the invention.

Elements in the figures are illustrated for simplicity and clarity andhave not necessarily been drawn to scale. For example, the dimensions ofsome of the elements in the figure may be exaggerated relative to otherelements to help to improve the understanding of the embodiments of thepresent invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention relates to a lens element intended to be worn in front ofan eye of a wearer.

In the reminder of the description, terms like «up», «bottom»,«horizontal», «vertical», «above», «below», «front», «rear» or otherwords indicating relative position may be used. These terms must beunderstood in the wearing conditions of the lens element.

In the context of the present invention, the term “lens element” canrefer to an uncut optical lens or a spectacle optical lens edged to fita specific spectacle frame or an ophthalmic lens and an optical deviceadapted to be positioned on the ophthalmic lens. The optical device maybe positioned on the front or back surface of the ophthalmic lens. Theoptical device may be an optical patch. The optical device may beadapted to be removably positioned on the ophthalmic lens for example aclip configured to be clipped on a spectacle frame comprising theophthalmic lens.

A lens element 10 according to the invention is adapted for a wearer andintended to be worn in front of an eye of said wearer.

As represented on FIG. 1, a lens element 10 according to the inventioncomprises:

-   -   a prescription portion 12, and    -   a plurality of at least three optical elements 14.

The prescription portion 12 is configured to provide to the wearer instandard wearing conditions and for foveal vision a first optical powerbased on the prescription of the wearer for correcting an abnormalrefraction of said eye of the wearer.

The wearing conditions are to be understood as the position of the lenselement with relation to the eye of a wearer, for example defined by apantoscopic angle, a Cornea to lens distance, a Pupil-cornea distance, acentre of rotation of the eye (CRE) to pupil distance, a CRE to lensdistance and a wrap angle.

The Cornea to lens distance is the distance along the visual axis of theeye in the primary position (usually taken to be the horizontal) betweenthe cornea and the back surface of the lens; for example equal to 12 mm.

The Pupil-cornea distance is the distance along the visual axis of theeye between its pupil and cornea; usually equal to 2 mm.

The CRE to pupil distance is the distance along the visual axis of theeye between its center of rotation (CRE) and cornea; for example equalto 11.5 mm.

The CRE to lens distance is the distance along the visual axis of theeye in the primary position (usually taken to be the horizontal) betweenthe CRE of the eye and the back surface of the lens, for example equalto 25.5 mm.

The pantoscopic angle is the angle in the vertical plane, at theintersection between the back surface of the lens and the visual axis ofthe eye in the primary position (usually taken to be the horizontal),between the normal to the back surface of the lens and the visual axisof the eye in the primary position; for example equal to 8°.

The wrap angle is the angle in the horizontal plane, at the intersectionbetween the back surface of the lens and the visual axis of the eye inthe primary position (usually taken to be the horizontal), between thenormal to the back surface of the lens and the visual axis of the eye inthe primary position for example equal to 0°.

An example of standard wearer condition may be defined by a pantoscopicangle of 8°, a Cornea to lens distance of 12 mm, a Pupil-cornea distanceof 2 mm, a CRE to pupil distance of 11.5 mm, a CRE to lens distance of25.5 mm and a wrap angle of 0°.

The term “prescription” is to be understood to mean a set of opticalcharacteristics of optical power, of astigmatism, of prismaticdeviation, determined by an ophthalmologist or optometrist in order tocorrect the vision defects of the eye, for example by means of a lenspositioned in front of his eye. For example, the prescription for amyopic eye comprises the values of optical power and of astigmatism withan axis for the distance vision.

Although the invention is not directed to progressive lenses, thewording used in this description is illustrated in FIGS. 1 to 10 ofdocument WO2016/146590 for a progressive lens. The skilled person canadapt the definitions for single vision lenses.

A progressive lens comprises at least one but preferably twonon-rotationally symmetrical aspheric surfaces, for instance but notlimited to, progressive surface, regressive surface, toric or atoricsurfaces.

As is known, a minimum curvature CURVmin is defined at any point on anaspherical surface by the formula:

${CURV}_{\min} = \frac{1}{R_{\max}}$

where Rmax is the local maximum radius of curvature, expressed in metersand CURVmin is expressed in dioptres.

Similarly, a maximum curvature CURVmax can be defined at any point on anaspheric surface by the formula:

${CURV}_{\max} = \frac{1}{R_{\min}}$

where Rmin is the local minimum radius of curvature, expressed in metersand CURVmax is expressed in dioptres.

It can be noticed that when the surface is locally spherical, the localminimum radius of curvature Rmin and the local maximum radius ofcurvature Rmax are the same and, accordingly, the minimum and maximumcurvatures CURVmin and CURVmax are also identical. When the surface isaspherical, the local minimum radius of curvature Rmin and the localmaximum radius of curvature Rmax are different.

From these expressions of the minimum and maximum curvatures CURVmin andCURVmax, the minimum and maximum spheres labeled SPHmin and SPHmax canbe deduced according to the kind of surface considered.

When the surface considered is the object side surface (also referred toas the front surface), the expressions are the following:

${{SPH}_{\min} = {{\left( {n - 1} \right)*{CURV}_{\min}} = \frac{n - 1}{R_{\max}}}},{and}$${SPH}_{\min} = {{\left( {n - 1} \right)*{CURV}_{\min}} = \frac{n - 1}{R_{\max}}}$

where n is the refractive index of the constituent material of the lens.

If the surface considered is an eyeball side surface (also referred toas the back surface), the expressions are the following:

${SPH}_{\min} = {{\left( {1 - n} \right)*{CURV}_{\min}} = {\frac{1 - n}{R_{\max}}\mspace{14mu} {and}}}$${SPH}_{\min} = {{\left( {1 - n} \right)*{CURV}_{\min}} = \frac{1 - n}{R_{\max}}}$

where n is the refractive index of the constituent material of the lens.

As is well known, a mean sphere SPHmean at any point on an asphericalsurface can also be defined by the formula:

SPH_(mean)=½(SPH_(min)+SPH_(max))

The expression of the mean sphere therefore depends on the surfaceconsidered:

-   -   if the surface is the object side surface,

${SPH}_{mean} = {\frac{n - 1}{2}\left( {\frac{1}{R_{\min}} + \frac{1}{R_{\max}}} \right)}$

-   -   if the surface is an eyeball side surface,

${SPH}_{mean} = {\frac{1 - n}{2}\left( {\frac{1}{R_{\min}} + \frac{1}{R_{\max}}} \right)}$

a cylinder CYL is also defined by the formula CYL=|SPH_(max)−SPH_(min)|.

The characteristics of any aspherical face of the lens may be expressedby the local mean spheres and cylinders. A surface can be considered aslocally non-spherical when the cylinder is at least 0.25 diopters.

For an aspherical surface, a local cylinder axis γAX may further bedefined. FIG. 7a illustrates the astigmatism axis γ as defined in theTABO convention and FIG. 7b illustrates the cylinder axis γAX in aconvention defined to characterize an aspherical surface.

The cylinder axis γAX is the angle of the orientation of the maximumcurvature CURVmax with relation to a reference axis and in the chosensense of rotation. In the above defined convention, the reference axisis horizontal (the angle of this reference axis is 0°) and the sense ofrotation is counter clockwise for each eye, when looking at the wearer(0°≤γAX≤180°). An axis value for the cylinder axis γAX of +45° thereforerepresents an axis oriented obliquely, which when looking at the wearer,extends from the quadrant located up on the right to the quadrantlocated down on the left.

Moreover, a progressive multifocal lens may also be defined by opticalcharacteristics, taking into consideration the situation of the personwearing the lenses.

FIGS. 8 and 9 are diagrammatic illustrations of optical systems of eyeand lens, thus showing the definitions used in the description. Moreprecisely, FIG. 8 represents a perspective view of such a systemillustrating parameters α and β used to define a gaze direction. FIG. 9is a view in the vertical plane parallel to the antero-posterior axis ofthe wearer's head and passing through the center of rotation of the eyein the case when the parameter β is equal to 0.

The center of rotation of the eye is labeled Q′. The axis Q′F′, shown onFIG. 9 in a dot-dash line, is the horizontal axis passing through thecenter of rotation of the eye and extending in front of the wearer—thatis the axis Q′F′ corresponding to the primary gaze view. This axis cutsthe aspherical surface of the lens on a point called the fitting cross,which is present on lenses to enable the positioning of lenses in aframe by an optician. The point of intersection of the rear surface ofthe lens and the axis Q′F′ is the point O. O can be the fitting cross ifit is located on the rear surface. An apex sphere, of center Q′, and ofradius q′, is tangential to the rear surface of the lens in a point ofthe horizontal axis. As examples, a value of radius q′ of 25.5 mmcorresponds to a usual value and provides satisfying results whenwearing the lenses.

A given gaze direction—represented by a solid line on FIG. 8—correspondsto a position of the eye in rotation around Q′ and to a point J of theapex sphere; the angle β is the angle formed between the axis Q′F′ andthe projection of the straight line Q′J on the horizontal planecomprising the axis Q′F′; this angle appears on the scheme on FIG. 3.The angle α is the angle formed between the axis Q′J and the projectionof the straight line Q′J on the horizontal plane comprising the axisQ′F′; this angle appears on the scheme on FIGS. 8 and 9. A given gazeview thus corresponds to a point J of the apex sphere or to a couple (α,β). The more the value of the lowering gaze angle is positive, the morethe gaze is lowering and the more the value is negative, the more thegaze is rising.

In a given gaze direction, the image of a point M in the object space,located at a given object distance, is formed between two points S and Tcorresponding to minimum and maximum distances JS and JT, which would bethe sagittal and tangential local focal lengths. The image of a point inthe object space at infinity is formed, at the point F′. The distance Dcorresponds to the rear frontal plane of the lens.

Ergorama is a function associating to each gaze direction the usualdistance of an object point. Typically, in far vision following theprimary gaze direction, the object point is at infinity. In near vision,following a gaze direction essentially corresponding to an angle α ofthe order of 35° and to an angle β of the order of 5° in absolute valuetoward the nasal side, the object distance is of the order of 30 to 50cm. For more details concerning a possible definition of an ergorama, USU.S. Pat. No. 6,318,859 may be considered. This document describes anergorama, its definition and its modeling method. For a method of theinvention, points may be at infinity or not. Ergorama may be a functionof the wearer's ametropia or wearer's addition.

Using these elements, it is possible to define a wearer optical powerand astigmatism, in each gaze direction. An object point M at an objectdistance given by the ergorama is considered for a gaze direction (α,β).An object proximity ProxO is defined for the point M on thecorresponding light ray in the object space as the inverse of thedistance MJ between point M and point J of the apex sphere:

ProxO=1/MJ

This enables to calculate the object proximity within a thin lensapproximation for all points of the apex sphere, which is used for thedetermination of the ergorama. For a real lens, the object proximity canbe considered as the inverse of the distance between the object pointand the front surface of the lens, on the corresponding light ray.

For the same gaze direction (α,β), the image of a point M having a givenobject proximity is formed between two points S and T which correspondrespectively to minimal and maximal focal distances (which would besagittal and tangential focal distances). The quantity ProxI is calledimage proximity of the point M:

${ProxI} = {\frac{1}{2}\left( {\frac{1}{JT} + \frac{1}{JS}} \right)}$

By analogy with the case of a thin lens, it can therefore be defined,for a given gaze direction and for a given object proximity, i.e. for apoint of the object space on the corresponding light ray, an opticalpower Pui as the sum of the image proximity and the object proximity.

Pui=ProxO+ProxI

With the same notations, an astigmatism Ast is defined for every gazedirection and for a given object proximity as:

${Ast} = \left| {\frac{1}{JT} - \frac{1}{JS}} \right|$

This definition corresponds to the astigmatism of a ray beam created bythe lens. It can be noticed that the definition gives, in the primarygaze direction, the classical value of astigmatism. The astigmatismangle, usually called axis, is the angle γ. The angle γ is measured inthe frame {Q′, xm, ym, zm} linked to the eye. It corresponds to theangle with which the image S or T i formed depending on the conventionused with relation to the direction zm in the plane {Q′, zm, ym}.

The optical power and astigmatism have been defined for foveal visionconsidering the light ray passing by the center of rotation of the eyeof the wearer.

The optical power and astigmatism may be defined in a similar manner forperipheral vision considering the light ray passing by the center of thepupil of the wearer as illustrated on FIG. 10 a.

Possible definitions of the optical power and the astigmatism of thelens, in the wearing conditions, can thus be calculated as explained inthe article by B. Bourdoncle et al., entitled “Ray tracing throughprogressive ophthalmic lenses”, 1990 International Lens DesignConference, D. T. Moore ed., Proc. Soc. Photo. Opt. Instrum. Eng.

The prescription portion 12 may further be configured to provide to thewearer for foveal vision a second optical power for foveal visiondifferent from the first optical power based on the prescription of thewearer.

In the sense of the invention, the two optical powers are considereddifferent when the difference between the two optical powers is greaterthan or equal to 0.5 D.

When the abnormal refraction of the eye of the person corresponds tomyopia the second optical power is greater than the first optical power.

When the abnormal refraction of the eye of the person corresponds tohyperopia, the second optical power is smaller than the first opticalpower.

The prescription portion is preferably formed as the portion other thanthe portions formed as the plurality of optical elements. In otherwords, the prescription portion is the complementary portion to theportions formed by the plurality of optical elements.

The prescription portion may have a continuous variation of opticalpower. For example, the prescription portion may have a progressiveaddition design.

The optical design of the prescription portion may comprise

-   -   a fitting cross where the optical power is negative,    -   a first zone extending in the temporal side of the prescription        portion when the lens element is being worn by a wearer. In the        first zone, the optical power increases when moving towards the        temporal side, and over the nasal side of the lens, the optical        power of the ophthalmic lens is substantially the same as at the        fitting cross.

Such optical design is disclosed in greater details in WO2016/107919.

Alternatively, the optical power in the prescription portion maycomprise at least one discontinuity.

As represented on FIG. 1, the lens element may be divided in fivecomplementary zones, a central zone 16 having an optical power equal tothe first refractive power and four quadrants Q1, Q2, Q3, Q4 at 45°, atleast one of the quadrant having at least a point where the opticalpower is equal to the second optical power.

In the sense of the invention the “quadrants at 45°” are to beunderstood as equal angular quadrant of 90° oriented in the directions45°/225° and 135°/315° according to the TABO convention as illustratedon FIG. 1.

Preferably, the central zone 16 comprises a framing reference point thatfaces the pupil of the wearer gazing straight ahead in standard wearingconditions and has a diameter greater than or equal to 4 mm and smallerthan or equal to 22 mm.

According to an embodiment of the invention at least the lower partquadrant Q4 has a second optical power for central vision different fromthe first optical power corresponding to the prescription for correctingthe abnormal refraction.

For example, the prescription portion has a progressive additiondioptric function. The progressive addition dioptric function may extendbetween the upper part quadrant Q2 and the lower part quadrant Q4.

Advantageously, such configuration allows compensation of accommodativelag when the person looks for example at near vision distances thanks tothe addition of the lens.

According to an embodiment, at least one of the temporal Q3 and nasal Q1quadrant has a second optical power. For example, the temporal Q3quadrant has a variation of power with the eccentricity of the lens.

Advantageously, such configuration increases the efficiency of theabnormal refraction control in peripheral vision with even more effectin horizontal axis.

According to an embodiment, the four quadrants Q1, Q2, Q3 and Q4 have aconcentric power progression.

According to an embodiment of the invention, the central zone of thelens corresponding to a zone centered on the optical center of the lenselement does not comprise optical elements. For example, the lenselement may comprise an empty zone centered on the optical center ofsaid lens element and having a diameter equal to 0.9 mm which does notcomprise optical elements.

The optical center of the lens element may correspond to the fittingpoint of the lens.

Alternatively, the optical elements may be disposed on the entiresurface of the lens element.

At least one optical element of the plurality of at least three opticalelements 14, has an optical function of not focusing an image on theretina of the eye of the wearer for peripheral vision.

In the sense of the invention “focusing” is to be understood asproducing a focusing spot with a circular section that can be reduced toa point in the focal plane.

Advantageously, such optical function of the optical element reduces thedeformation of the retina of the eye of the wearer in peripheral vision,allowing to slow down the progression of the abnormal refraction of theeye of the person wearing the lens element.

The optical elements may be as represented on FIG. 1, non-contiguousoptical elements.

In the sense of the invention, two optical elements located on a surfaceof the lens element are non-contiguous if along all the paths supportedby said surface that links the two optical elements one does reach thebasis surface on which the optical elements are located.

When the surface on which the at least two optical elements are locatedis spherical, the basis surface corresponds to said spherical surface.In other words, two optical elements located on a spherical surface arenon-contiguous if along all paths linking them and supported by saidspherical surface one reaches the spherical surface.

When the surface on which the at least two optical elements are locatedis non-spherical, the basis surface corresponds to the local sphericalsurface that best fit said non-spherical surface. In other words, twooptical elements located on a non-spherical surface are non-contiguousif along all paths linking them and supported by said non-sphericalsurface one reaches the spherical surface that best fit thenon-spherical surface.

As illustrated on FIG. 12, the plurality of optical elements 14 maycomprises at least two optical elements that are contiguous.

In the sense of the invention, two optical elements located on a surfaceof the lens element are contiguous if there is a path supported by saidsurface that links the two optical elements and if along said path onedoes not reach the basis surface on which the optical elements arelocated.

When the surface on which the at least two optical elements are locatedis spherical, the basis surface corresponds to said spherical surface.In other words, two optical elements located on a spherical surface arecontiguous if there is a path supported by said spherical surface andlinking them and if along said path one may not reach the sphericalsurface.

When the surface on which the at least two optical elements are locatedis non-spherical, the basis surface corresponds to the local sphericalsurface that best fit said non-spherical surface. In other words, twooptical elements located on a non-spherical surface are contiguous ifthere is a path supported by said non-spherical surface and linking themand if along said path one may not reach the spherical surface that bestfit the non-spherical surface.

Advantageously, having contiguous optical elements helps improving theaesthetic of the lens element and is easier to manufacture.

At least one, preferably all of the, optical element of the plurality ofoptical elements 14, has an optical function of not focusing an image onthe retina of the eye of the wearer, in particular for peripheral visionand preferably for central and peripheral vision.

Advantageously, such optical function of the optical element reduces thedeformation of the retina of the eye of the wearer in peripheral vision,allowing to slow down the progression of the abnormal refraction of theeye of the person wearing the lens element.

According to a preferred embodiment of the invention, the at least twocontiguous optical elements are independent.

In the sense of the invention, two optical elements are considered asindependent if producing independent images.

In particular, when illuminated by a parallel beam “in central vision”,each “independent contiguous optical element” forms on a plane in theimage space a spot associated with it. In other words, when one of the“optical element” is hidden, the spot disappears even if this opticalelement is contiguous with another optical element.

For the classic Fresnel ring (carrying a single power) as disclosed inU.S. Pat. No. 7,976,158, said Fresnel ring produces a single spot whoseposition is not changed if one conceals a small part of the ring. TheFresnel ring cannot therefore be considered as a succession of“independent contiguous optical element”. According to an embodiment ofthe invention, the optical elements have specific sizes. In particular,the optical elements have a contour shape being inscribable in a circlehaving a diameter greater than or equal to 0.8 mm and smaller than orequal to 3.0 mm, preferably greater than or equal to 1.0 mm and smallerthan 2.0 mm.

According to embodiments of the invention, the optical elements arepositioned on a network.

The network on which the optical elements are positioned may be astructured network as illustrated on FIGS. 12 to 16.

In the embodiments illustrated on FIGS. 12 to 15 the optical elementsare positioned along a plurality of concentric rings.

The concentric rings of optical elements may be annular rings.

According to an embodiment of the invention, the lens element furthercomprises at least four optical elements. The at least four opticalelements are organized in at least two groups of optical elements, eachgroup of optical element being organized in at least two concentricrings having the same center, the concentric ring of each group ofoptical element being defined by an inner diameter and an outerdiameter.

According to an embodiment of the invention, the optical elements ofeach group of optical elements are contiguous.

The inner diameter of a concentric ring of each group of opticalelements corresponds to the smallest circle that is tangent to at leastone optical element of said group of optical elements. The outerdiameter of a concentric ring of optical element corresponds to thelargest circle that is tangent to at least one optical element of saidgroup.

For example, the lens element may comprise n rings of optical elements,f_(inner 1) referring to the inner diameter of the concentric ring whichis the closest to the optical center of the lens element, f_(outer 1)referring to the outer diameter of the concentric ring which is theclosest to the optical center of the lens element, f_(inner n) referringto the inner diameter of the ring which is the closest to the peripheryof the lens element, and f_(outer n) referring to the outer diameter ofthe concentric ring which is the closest to the periphery of the lenselement.

The distance D_(i) between two successive concentric rings of opticalelements i and i+1 may be expressed as:

D _(i) =|f _(inner i+1) −f _(outer i)|,

wherein f_(outer i) refers to the outer diameter of a first ring ofoptical elements i and f_(inner i+1) refers to the inner diameter of asecond ring of optical elements i+1 that is successive to the first oneand closer to the periphery of the lens element.

According to another embodiment of the invention, the optical elementsare organized in concentric rings centered on the optical center of thesurface of the lens element on which the optical elements are disposedand linking the geometrical center of each optical element.

For example, the lens element may comprise n rings of optical elements,f₁ referring to the diameter of the ring which is the closest to theoptical center of the lens element and f_(n) referring to the diameterof the ring which is the closest to the periphery of the lens element.

The distance D_(i) between two successive concentric rings of opticalelements i and i+1 may be expressed as:

${D_{i} = \left| {f_{i + 1} - f_{i} - \frac{d_{i + 1}}{2} - \frac{d_{i}}{2}} \right|},$

wherein f_(i) refers to the diameter of a first ring of optical elementsi and f_(i+1) refers to the diameter of a second ring of opticalelements i+1 that is successive to the first one and closer to theperiphery of the lens element, and

wherein d_(i) refers to the diameter of the optical elements on thefirst ring of optical elements and d_(i+1) refers to the diameter of theoptical elements on the second ring of optical elements that issuccessive to the first ring and closer to the periphery of the lenselement. The diameter of the optical element corresponds to the diameterof the circle in which the contour shape of the optical element isinscribed.

The concentric rings of optical elements may be annular rings.

Advantageously, the optical center of the lens element and the center ofthe concentric rings of optical elements coincide. For example, thegeometrical center of the lens element, the optical center of the lenselement, and the center of the concentric rings of optical elementscoincide.

In the sense of the invention, the term coincide should be understood asbeing really close together, for example distanced by less than 1.0 mm.

The distance D_(i) between two successive concentric rings may varyaccording to i. For example, the distance D_(i) between two successiveconcentric rings may vary between 2.0 mm and 5.0 mm.

According to an embodiment of the invention, the distance D_(i) betweentwo successive concentric rings of optical elements is greater than 2.00mm, preferably 3.0 mm, more preferably 5.0 mm.

Advantageously, having the distance D_(i) between two successiveconcentric rings of optical elements greater than 2.00 mm allowsmanaging a larger refraction area between these rings of opticalelements and thus provides better visual acuity.

Considering an annular zone of the lens element having an inner diametergreater than 9 mm and an outer diameter smaller than 57 mm, having ageometrical center located at a distance of the optical center of thelens element smaller than 1 mm, the ratio between the sum of areas ofthe parts of optical elements located inside said circular zone and thearea of said circular zone is comprised between 20% and 70%, preferablybetween 30% and 60%, and more preferably between 40% and 50%.

In other words, the inventors have observed that for a given value ofthe abovementioned ratio, the organization of optical elements inconcentric rings, where these rings are spaced by a distance greaterthan 2.0 mm, allows providing annular zones of refractive area easier tomanufacture than the refractive area managed when optical element aredisposed in hexagonal network or randomly disposed on the surface of thelens element. thereby provide a better correction of the abnormalrefraction of the eye and thus a better visual acuity.

According to an embodiment of the invention, the diameter di of alloptical elements of the lens element are identical.

According to an embodiment of the invention, the distance D_(i) betweentwo successive concentric rings i and i+1 may increase when i increasestowards the periphery of the lens element.

The concentric rings of optical elements may have a diameter comprisedbetween 9 mm and 60 mm.

According to an embodiment of the invention, the lens element comprisesoptical elements disposed in at least 2 concentric rings, preferablymore than 5, more preferably more than 10 concentric rings. For example,the optical elements may be disposed in 11 concentric rings centered onthe optical center of the lens.

On FIG. 12, the optical elements are micro-lenses positioned along a setof 5 concentric rings. The optical power and/or cylinder of themicro-lenses may be different depending on their position along theconcentric rings.

On FIG. 13, the optical elements correspond to different sectors ofconcentric circles.

On FIG. 14b , the optical elements correspond to part of purecylindrical concentric rings as illustrated on FIG. 14a . In thisexample, the optical elements have constant power but a variablecylindrical axis.

According to an embodiment of the invention, for example illustrated onFIG. 12, the lens element may further comprise optical elements 14positioned radially between two concentric rings. In the exampleillustrated on FIG. 12, only 4 optical elements are placed between twoconcentric rings, however, may more optical elements may be positionedbetween both rings.

The optical elements may be placed on a structured network that is asquared network or a hexagonal network or a triangle network or anoctagonal network.

Such embodiment of the invention is illustrated on FIG. 16 where theoptical elements 14 are place on a squared network.

Alternatively, the optical elements may be placed on a random structurenetwork such as a Voronoid network as illustrated on FIG. 17.

Advantageously, having the optical elements placed on a random structurelimits the risk of light scattering or diffraction.

Different junctions between two contiguous optical elements arepossible.

For example, as illustrated on FIGS. 18a and 18b , at least part, forexample all of the optical elements have a constant optical power and adiscontinue first derivative between two contiguous optical elements. Inthe examples illustrated on FIGS. 18a and 18b , teta is the angularcoordinate in polar reference. As one can observe in this embodiment,there is no area between the contiguous optical elements with no sphere.

Alternatively, as illustrated on FIGS. 19a and 19b , at least part, forexample all, of the optical elements have a varying optical power and acontinue first derivative between two contiguous optical elements.

To obtain such variation, here one may use two constant powers, onepositive and one negative. The area of the negative power is muchsmaller than the area of the positive power, so that globally one has apositive power effect.

An important point in this embodiment illustrated on FIGS. 19a and 19bis that the Z coordinate is always positive compared to the refractionarea.

As illustrated on FIG. 2, a lens element 10 according to the inventioncomprises an object side surface F1 formed as a convex curved surfacetoward an object side, and an eye side surface F2 formed as a concavesurface having a different curvature than the curvature of the objectside surface F1.

According to an embodiment of the invention, at least part, for exampleall, of the optical elements are located on the front surface of thelens element.

At least part, for example all, of the optical elements may be locatedon the back surface of the lens element.

At least part, for example all, of the optical elements may be locatedbetween the front and back surfaces of the lens element. For example,the lens element may comprise zones of different refractive indexforming the optical elements.

According to an embodiment of the invention, at least one of the opticalelements has an optical function of focusing an image for peripheralvision on a position other than the retina.

Preferably, at least 50%, for example at least 80%, for example all, ofthe optical elements have an optical function of focusing an image forperipheral vision on a position other than the retina.

According to a preferred embodiment of the invention, all of the opticalelements are configured so that the mean focus of the light rays passingthrough each optical element is at a same distance to the retina of thewearer, at least for peripheral vision.

The optical function, in particular the dioptric function, of eachoptical element may be optimized so as to provide a focus image, inparticular in peripheral vision, at a constant distance of the retina ofthe eye of the wearer. Such optimization requires adapting the dioptricfunction of each of the optical element depending on their position onthe lens element.

In particular, the inventors have determined that spot diagram of thebeam of light passing through a spherical 3D shaped micro lens analyzedin peripheral vision (30° from the pupil center) is not a point.

To obtain a point the inventors have determined that the optical elementshould have a cylindrical power, for example have a toric shape.

The kind of astigmatism commonly encountered as a vision defect is aresult of different lens curvatures in different planes. But evenspherical lenses that are perfectly symmetrical exhibit a type ofastigmatism for light which approaches the lens from a point off theoptic axis. As illustrated on FIG. 10b , oblique astigmatism is anaberration of off-axis rays that causes radial and tangential lines inthe object plane to focus sharply at different distances in the imagespace

Therefore, looking at a spherical lens through its optical axis does notgenerate astigmatism. If the optical elements are seen so that the axisof the optical element passes through the eye, in particular through thecenter of the pupil for peripheral vision, then there is no astigmatism.However, in all other cases, and even more so when the optical elementsare excentric compared to the gazing direction, in particular for theperipheral vision, one has an oblique astigmatism. The light passingthrough the optical element does not “see” the same power in all themeridians, i.e. from the center to the edge of the optical elements.

According to an embodiment of the invention, the optical elements areconfigured so that at least along one section of the lens the meansphere of the optical elements increases from a point of said sectiontowards the periphery of said section.

The optical elements may further be configured so that at least alongone section of the lens, for example at least the same section as theone along which the mean sphere of the optical elements increases, thecylinder increases from a point of said section, for example the samepoint as for the mean sphere, towards the peripheral part of saidsection.

Advantageously, having optical elements configured so that along atleast one section of the lens the mean sphere and/or mean cylinder ofoptical elements increases from a point of said section towards theperipheral part of said section allows increasing the defocus of thelight rays in front the retina in case of myopia or behind the retina incase of hyperopia.

In other words, the inventors have observed that having optical elementsconfigured so that along at least one section of the lens the meansphere of optical elements increases from a point of said sectiontowards the peripheral part of said section helps slow down theprogression of abnormal refraction of the eye such as myopia orhyperopia.

The optical elements may be configured so that that along the at leastone section of the lens the mean sphere and/or the cylinder of opticalelements increases from the center of said section towards theperipheral part of said section.

According to an embodiment of the invention, the optical elements areconfigured so that in standard wearing condition the at least onesection is a horizontal section.

The mean sphere and/or the cylinder may increase according to anincrease function along the at least one horizontal section, theincrease function being a Gaussian function. The Gaussian function maybe different between the nasal and temporal part of the lens so as totake into account the dissymmetry of the retina of the person.

Alternatively, the mean sphere and/or the cylinder may increaseaccording to an increase function along the at least one horizontalsection, the increase function being a Quadratic function. The Quadraticfunction may be different between the nasal and temporal part of thelens so as to take into account the dissymmetry of the retina of theperson.

According to an embodiment of the invention, the mean sphere and/or thecylinder of optical elements increases from a first point of saidsection towards the peripheral part of said section and decreases from asecond point of said section towards the peripheral part of saidsection, the second point being closer to the peripheral part of saidsection than the first point.

Such embodiment is illustrated in table 1 that provides the mean sphereof optical elements according to their radial distance to the opticalcenter of the lens element.

In the example of table 1, the optical elements are micro-lenses placedon a spherical front surface having a curvature of 329.5 mm and the lenselement is made of an optical material having a refractive index of1.591, the prescribed optical power of the wearer is of 6 D. The opticalelement is to be worn in standard wearing conditions and the retina ofthe wearer is considered as having a defocus of 0.8 D at an angle of30°. The optical elements are determined to have a peripheral defocus of2 D.

TABLE 1 Distance to optical center (mm) Mean sphere of optical element(D) 0 1.992 5 2.467 7.5 2.806 10 3.024 15 2.998 20 2.485

As illustrated in table 1, starting close to the optical center of thelens element, the mean sphere of the optical elements increases towardsthe peripheral part of said section and then decreases towards theperipheral part of said section.

According to an embodiment of the invention, the mean cylinder ofoptical elements increases from a first point of said section towardsthe peripheral part of said section and decreases from a second point ofsaid section towards the peripheral part of said section, the secondpoint being closer to the peripheral part of said section than the firstpoint.

Such embodiment is illustrated in tables 2 and 3 that provides theamplitude of the cylinder vector projected on a first direction Ycorresponding to the local radial direction and a second direction Xorthogonal to the first direction.

In the example of table 2, the optical elements are micro-lenses placedon a spherical front surface having a curvature of 167.81 mm and thelens element is made of a material having a refractive index of 1.591,the prescribed optical power of the wearer is of −6 D. The lens elementis to be worn in standard wearing conditions and the retina of thewearer is considered as having a defocus of 0.8 D at an angle of 30°.The optical elements are determined to provide a peripheral defocus of 2D.

In the example of table 3, the optical elements are micro-lenses placedon a spherical front surface having a curvature of 167.81 mm and thelens element is made of a material having a refractive index of 1.591,the prescribed optical power of the wearer is of −1 D. The lens elementis to be worn in standard wearing conditions and the retina of thewearer is considered as having a defocus of 0.8 D_(i) at an angle of30°. The optical elements are determined to provide a peripheral defocusof 2 D.

TABLE 2 gazing direction Px Py Cylinder (in degree) (in Diopter) (inDiopter) (in Diopter) 0 1.987 1.987 1.987 18.581 2.317 2.431 2.37427.002 2.577 2.729 2.653 34.594 2.769 2.881 2.825 47.246 2.816 2.6592.7375 57.02 2.446 1.948 2.197

TABLE 3 gazing direction Px Py Cylinder (in degree) (in Diopter) (inDiopter) (in Diopter) 0 1.984 1.984 1.984 18.627 2.283 2.163 2.22327.017 2.524 2.237 2.3805 34.526 2.717 2.213 2.465 46.864 2.886 1.9432.4145 56.18 2.848 1.592 2.22

As illustrated in tables 2 and 3, starting close to the optical centerof the lens element, the cylinder of the optical elements increasestowards the peripheral part of said section and then decreases towardsthe peripheral part of said section.

According to an embodiment of the invention, the prescription portioncomprises an optical center and optical elements are configured so thatalong any section passing through the optical center of the lens themean sphere and/or the cylinder of the optical elements increases fromthe optical center towards the peripheral part of the lens.

For example, the optical elements may be regularly distributed alongcircles centered on the optical center of the portion.

The optical elements on the circle of diameter 10 mm and centered on theoptical center of the prescription portion may be micro lenses having amean sphere of 2.75 D.

The optical elements on the circle of diameter 20 mm and centered on theoptical center of the prescription portion may be micro lenses having amean sphere of 4.75 D.

The optical elements on the circle of diameter 30 mm and centered on theoptical center of the prescription portion may be micro lenses having amean sphere of 5.5 D.

The optical elements on the circle of diameter 40 mm and centered on theoptical center of the prescription portion may be micro lenses having amean sphere of 5.75 D.

The cylinder of the different micro lenses may be adjusted based on theshape of the retina of the person.

According to an embodiment of the invention, the prescription portioncomprises a far vision reference point, a near vision reference, and ameridian joining the far and near vision reference points. For example,the prescription portion may comprise a progressive additional lensdesign adapted to the prescription of the person or adapted to slow downthe progression of the abnormal refraction of the eye of the personwearing the lens element.

Preferably, according to such embodiment, the optical elements areconfigured so that in standard wearing conditions along any horizontalsection of the lens the mean sphere and/or the cylinder of the opticalelements increases from the intersection of said horizontal section withthe meridian line towards the peripheral part of the lens.

The meridian line corresponds to the locus of the intersection of themain gaze direction with the surface of the lens.

The mean sphere and/or the mean cylinder increase function along thesections may be different depending on the position of said sectionalong the meridian line.

In particular, the mean sphere and/or the mean cylinder increasefunction along the sections are unsymmetrical. For example, the meansphere and/or the mean cylinder increase function are unsymmetricalalong vertical and/or horizontal section in standard wearing conditions.

According to an embodiment of the invention, at least one of the opticalelements has a non-focused optical function in standard wearingconditions and for peripheral vision.

Preferably at least 50%, for example at least 80%, for example all, ofthe optical elements 14 have a non-focused optical function in standardwearing conditions and for peripheral vision.

In the sense of the invention, a “non-focused optical function” is to beunderstood as not having a single focus point in standard wearingconditions and for peripheral vision.

Advantageously, such optical function of the optical element reduces thedeformation of the retina of the eye of the wearer, allowing to slowdown the progression of the abnormal refraction of the eye of the personwearing the lens element.

The at least one element having a non-focused optical function istransparent. Advantageously, the non-contiguous optical elements are notvisible on the lens element and do not affect the aesthetic of the lenselement.

According to an embodiment of the invention, the lens element maycomprise an ophthalmic lens bearing the prescription portion and aclip-on bearing the plurality of at least three optical elements adaptedto be removably attached to the ophthalmic lens when the lens element isworn.

Advantageously, when the person is in a far distance environment,outside for example, the person may separate the clip-on from theophthalmic lens and eventually substitute a second clip-on free of anyof at least three optical elements. For example, the second clip-on maycomprise a solar tint. The person may also use the ophthalmic lenswithout any additional clip-on.

The optical element may be added to the lens element independently oneach surface of the lens element.

One can add these optical elements on a defined array like square orhexagonal or random or other.

The optical element may cover specific zones of the lens element, likeat the center or any other area.

The optical element density or the quantity of power may be adjusteddepending on zones of the lens element. Typically, the optical elementmay be positioned in the periphery of the lens element, in order toincrease the effect of the optical element on myopia control, so as tocompensate peripheral defocus due to the peripheral shape of the retinafor example.

According to a preferred embodiment of the invention, every circularzone having a radius comprised between 2 and 4 mm comprising ageometrical center located at a distance of the optical center of thelens element greater or equal to said radius+5 mm, the ratio between thesum of areas of the parts of optical elements located inside saidcircular zone and the area of said circular zone is comprised between20% and 70%, preferably between 30% and 60%, and more preferably between40% and 50%.

The optical elements can be made using different technologies as directsurfacing, molding, casting or injection, embossing, filming, orphotolithography etc. . . . .

According to an embodiment of the invention, at least one, for exampleall, of the optical elements has a shape configured so as to create acaustic in front of the retina of the eye of the person. In other words,such optical element is configured so that every section plane where thelight flux is concentrated if any, is located in front of the retina ofthe eye of the person.

According to an embodiment of the invention, the at least one, forexample all, of the optical element having a non-spherical opticalfunction is a multifocal refractive micro-lens.

In the sense of the invention, an optical element is “multifocalrefractive micro-lens” includes bifocals (with two focal powers),trifocals (with three focal powers), progressive addition lenses, withcontinuously varying focal power, for example aspherical progressivesurface lenses.

In the sense of the invention, a “micro-lens” has a contour shape beinginscribable in a circle having a diameter greater than or equal to 0.8mm and smaller than or equal to 3.0 mm, preferably greater than or equalto 1.0 mm and smaller than 2.0 mm.

According to an embodiment of the invention, at least one of the opticalelement, preferably more than 50%, more preferably more than 80% of theoptical elements are aspherical microlenses. In the sense of theinvention, aspherical microlenses have a continuous power evolution overtheir surface.

An aspherical microlens may have an asphericity comprised between 0.1Dand 3D. The asphericity of an aspherical microlens corresponds to theratio of optical power measured in the center of the microlens and theoptical power measured in the periphery of the microlens.

The center of the microlens may be defined by a spherical area centeredon the geometrical center of the microlens and having a diametercomprised between 0.1 mm and 0.5 mm, preferably equal to 2.0 mm.

The periphery of the microlens may be defined by an annular zonecentered on the geometrical center of the microlens and having an innerdiameter comprised between 0.5 mm and 0.7 mm and an outer diametercomprised between 0.70 mm and 0.80 mm.

According to an embodiment of the invention, the aspherical microlenseshave an optical power in their geometrical center comprised between 2.0Dand 7.0D in absolute value, and an optical power in their peripherycomprised between 1.5D and 6.0D in absolute value.

The asphericity of the aspherical microlenses before the coating of thesurface of the lens element on which the optical elements are disposedmay vary according to the radial distance from the optical center ofsaid lens element.

Additionally, the asphericity of the aspherical microlenses after thecoating of the surface of the lens element on which the optical elementsare disposed may further vary according to the radial distance from theoptical center of said lens element.

According to an embodiment of the invention, the at least one multifocalrefractive micro-lens has a toric surface. A toric surface is a surfaceof revolution that can be created by rotating a circle or arc about anaxis of revolution (eventually positioned at infinity) that does notpass through its center of curvature.

Toric surface lenses have two different radial profiles at right anglesto each other, therefore producing two different focal powers.

Toric and spheric surface components of toric lenses produce anastigmatic light beam, as opposed to a single point focus.

According to an embodiment of the invention, the at least one of theoptical elements having a non-spherical optical function, for exampleall, of the optical elements is a toric refractive micro-lens. Forexample, a toric refractive micro-lens with a sphere power value greaterthan or equal to 0 diopter (δ) and smaller than or equal to +5 diopters(δ), and cylinder power value greater than or equal to 0.25 Diopter (δ).

Oblique effects of peripheral light rays passing through sphericalmicro-lenses generate an oblique astigmatism, and thus unfocused lightbeams.

Advantageously, having toric micro-lenses allows focusing the light rayspassing through the micro-lenses at a given distance from the retina ofthe wearer.

As a specific embodiment, the toric refractive microlens may be a purecylinder, meaning that minimum meridian power is zero, while maximummeridian power is strictly positive, for instance less than 5 Diopters.

According to an embodiment of the invention, at least one, for exampleall, of the optical element, is made of a birefringent material. Inother words, the optical element is made of a material having arefractive index that depends on the polarization and propagationdirection of light. The birefringence may be quantified as the maximumdifference between refractive indices exhibited by the material.

According to an embodiment of the invention, at least one, for exampleall of the optical element, has discontinuities, such as a discontinuoussurface, for example Fresnel surfaces and/or having a refractive indexprofile with discontinuities.

FIG. 3 represents an example of a Fresnel height profile of an opticalelement that may be used for the invention.

According to an embodiment of the invention, at least one, for exampleall of the optical element, is made of a diffractive lens.

FIG. 4 represents an example of a diffractive lens radial profile of anoptical element that may be used for the invention.

At least one, for example all, of the diffractive lenses may comprise ametasurface structure as disclosed in WO2017/176921.

The diffractive lens may be a Fresnel lens whose phase function ψ(r) hasπ phase jumps at the nominal wavelength, as seen in FIG. 5. One may givethese structures the name “π-Fresnel lenses” for clarity's sake, asopposition to unifocal Fresnel lenses whose phase jumps are multiplevalues of 2π. The π-Fresnel lens whose phase function is displayed inFIG. 5 diffracts light mainly in two diffraction orders associated todioptric powers 0 δ and a positive one P, for example 3 δ.

According to an embodiment of the invention, at least one, for exampleall of the optical element, is a multifocal binary component.

For example, a binary structure, as represented in FIG. 6a , displaysmainly two dioptric powers, denoted −P/2 and P/2. When associated to arefractive structure as shown in FIG. 6b , whose dioptric power is P/2,the final structure represented in FIG. 6c has dioptric powers 0 δ andP. The illustrated case is associated to P=3 δ.

According to an embodiment of the invention, at least one, for exampleall of the optical element, is a pixelated lens. An example ofmultifocal pixelated lens is disclosed in Eyal Ben-Eliezer et al,APPLIED OPTICS, Vol. 44, No. 14, 10 May 2005.

According to an embodiment of the invention, at least one, for exampleall of the optical element, has an optical function with high orderoptical aberrations. For example, the optical element is a micro-lenscomposed of continuous surfaces defined by Zernike polynomials.

According to an embodiment of the invention, at least one, for exampleat least 70%, for example all optical elements are active opticalelement that may be activated manually or automatically by an opticallens controller device.

The active optical element may comprise a material having a variablerefractive index whose value is controlled by the optical lenscontroller device.

The invention also relates to a method for determining a lens elementadapted to slow down the progression of the abnormal refraction of theeye of a wearer.

As illustrated on FIG. 11, the method of the invention comprises atleast:

-   -   a wearer prescription data providing step S1,    -   a wearing condition data providing step S2,    -   a wearer retina data providing step S3, and    -   a lens element determining step S4,

During the wearer prescription data providing step S1, wearerprescription data relating the prescription of the wearer are provided.

Wearing condition data relating to wearing conditions of the lenselement by the wearer are provided during the wearer condition dataproviding step S2.

According to an embodiment of the invention, the wearing condition dataprovided during the wearing condition data providing step correspond tostandard wearing conditions.

Alternatively, the wearing condition data provided during the wearingcondition data providing step correspond to wearing conditions measuredon the wearer or customized for example based on morphological orpostural data relating to the wearer.

During the wearer retina data providing step S3, retina data relating tothe shape of the retina of the wearer in the same reference frame as thewearing conditions are provided.

According to an embodiment of the invention, the wearer retina dataprovided during the wearer retina data providing step correspond tostandard retina shape.

Examples of standard retina shapes are disclosed in “Refractive error,axial length, and relative peripheral refractive error before and afterthe onset of myopia” by Mutti D O1, Hayes J R, Mitchell G L, Jones L A,Moeschberger M L, Cotter S A, Kleinstein R N, Manny R E, Twelker J D,Zadnik K; CLEERE Study Group, Invest Ophthalmol Vis Sci. 2007 June;48(6):2510-9.

Further examples of standard retina shapes are disclosed in “Peripheralrefraction along the horizontal and vertical visual fields in myopia”,by Atchison D A1, Pritchard N, Schmid K L, Vision Res. 2006 April;46(8-9):1450-8.

Additional examples of standard retina shapes are disclosed in“Peripheral Refraction and Ocular Shape in Children”, by Donald O.Mutti, Robert I. Sholtz, Nina E. Friedman, and Karla Zadnik in IOVS,April 2000, Vol. 41, No. 5.

Alternatively, the wearer retina data provided during the wearer retinadata providing step may correspond to the shape of the retina measuredon the wearer or customized for example based on morphological orprescription of the wearer.

During the lens element determining step S4 a lens element comprising aprescription portion and a plurality of at least three optical elementsis determined.

The lens element is determined so that the prescription portion providesin wearing conditions corresponding to the wearing data and for fovealvision a first optical power based on the prescription of the wearer.

Furthermore, at least one optical element, for example at least 50%,preferably at least 80% of the optical elements, is determined to has tohave an optical function of not focusing an image on the retina of theeye for peripheral vision.

Advantageously the determined lens element provided for foveal visioncorrection corresponding to the prescription of the wearer and for

According to an embodiment of the invention, during the lens elementdetermining step at least 50%, for example at least 80%, of the opticalelements are determined so as to focus an image at a given distance ofthe retina. Said distance is defined for each optical element along theaxis linking a reference point of said optical element, for example theoptical center of the lens element, and the center of the pupil of thewearer.

Alternatively, at least 50%, for example at least 80%, of the opticalelements are determined so as to focus an image at a same distance ofthe retina along the axis linking a reference point of each opticalelement and the center of the pupil of the wearer.

As illustrated on FIG. 11, the method of the invention may furthercomprise a front surface data providing step S40.

During the front surface data providing step S40, front surface datarepresentative of the front surface of the lens element are provided.

According to such embodiment, during the lens element determining stepthe shape of the back surface and the optical elements to be placed onthe front surface are determined so that the prescription portionprovides in wearing conditions corresponding to the wearing data and forfoveal vision a first optical power based on the prescription of thewearer and at least one optical element has an optical function of notfocusing an image on the retina of the eye for peripheral vision.

According to a preferred embodiment, during the lens element determiningstep the shape of the back surface is determined so that theprescription portion provides in wearing conditions corresponding to thewearing data and for foveal vision a first optical power based on theprescription of the wearer.

The optical elements are determined so as to be placed either on thefront or back surface of the lens determined previously and to focusimages at a given distance of the retina of the eye for peripheralvision.

As seen, it is possible to optimize the optical elements themselves, butalso, it is possible to optimize the opposite lens surface, or combinethe two, to reduce aberrations of the optical element for peripheralvision. In this case, it would be a compromise between the optimizationof the prescription portion and the optical elements. This isparticularly relevant when the optical element are mass produced (mold,film embedded in a lens).

The invention has been described above with the aid of embodimentswithout limitation of the general inventive concept.

Many further modifications and variations will be apparent to thoseskilled in the art upon making reference to the foregoing illustrativeembodiments, which are given by way of example only and which are notintended to limit the scope of the invention, that being determinedsolely by the appended claims.

In the claims, the word “comprising” does not exclude other elements orsteps, and the indefinite article “a” or “an” does not exclude aplurality. The mere fact that different features are recited in mutuallydifferent dependent claims does not indicate that a combination of thesefeatures cannot be advantageously used. Any reference signs in theclaims should not be construed as limiting the scope of the invention.

1. A lens element intended to be worn in front of an eye of a wearercomprising: a prescription portion configured to provide to the wearer,in standard wearing conditions and for foveal vision a first opticalpower, corresponding to a prescription of the wearer for correcting anabnormal refraction of said eye of the wearer; and at least threeoptical elements, at least one optical element of the at least threeoptical elements having an optical function of not focusing an image ona retina of the eye in standard wearing conditions and for peripheralvision to slow down progression of the abnormal refraction of the eye,wherein the at least three optical elements are configured so that alongat least one section of the lens element, a mean sphere of the at leastthree optical elements increases from a first point of the at least onesection towards a peripheral part of the at least one section by atleast 0.5 D, and decreases from a second point of the at least onesection towards the peripheral part of the at least one section by atleast 0.5 D, the second point being closer to the peripheral part of theat least one section than the first point.
 2. The lens element accordingto claim 1, wherein at least one optical element of the at least threeoptical elements has an optical function of focusing an image on aposition other than the retina in standard wearing conditions and forperipheral vision.
 3. The lens element according to claim 1, wherein atleast one optical element of the at least three optical elements has anon-focused optical function in standard wearing conditions and forperipheral vision.
 4. The lens element according to claim 1, wherein atleast one optical element of the at least three optical elements has acylindrical power.
 5. The lens element according to claim 1, wherein theat least three optical elements are configured so that along at leastone section of the lens element a mean sphere of optical elementsincreases from a point of said section towards a periphery of saidsection.
 6. The lens element according to claim 1, wherein the at leastthree optical elements are configured so that along at least one sectionof the lens element a cylinder of optical elements increases from apoint of said section towards a periphery of said section.
 7. The lenselement according to claim 1, wherein the at least three opticalelements are configured so that along at least one section of the lenselement a mean sphere and/or a cylinder of optical elements increasesfrom a center of said section towards a periphery of said section. 8.The lens element according to claim 1, wherein the prescription portionincludes an optical center and the at least three optical elements areconfigured so that along any section passing through the optical centerof the lens element a mean sphere and/or a cylinder of optical elementsincreases from the optical center towards a periphery of the lenselement.
 9. The lens element according to claim 1, wherein theprescription portion is formed as a portion other than portions formedas the at least three optical elements.
 10. The lens element accordingto claim 1, wherein for every circular zone having a radius comprisedbetween 2 mm and 4 mm including a geometrical center located at adistance of a framing reference that faces a pupil of the user gazingstraight ahead in standard wearing conditions greater or equal to saidradius+5 mm, a ratio between a sum of areas of parts of optical elementslocated inside said circular zone and an area of said circular zone iscomprised between 20% and 70% of the lens element.
 11. The lens elementaccording to claim 1, wherein the at least three optical elements arenon-contiguous.
 12. The lens element according to claim 1, wherein atleast part of the at least three optical elements are located on a frontsurface of an ophthalmic lens corresponding to the lens element.
 13. Amethod for determining a lens element adapted to slow down progressionof abnormal refraction of an eye of a wearer, the method comprising:obtain wearer prescription data relating a prescription of the wearer;obtaining wearing condition data relating to wearing conditions of thelens element by the wearer; obtaining wearer retina data relating to ashape of a retina of the wearer; and determining a lens elementincluding a prescription portion and at least three optical elements sothat the prescription portion provides, in searing conditionscorresponding to the wearing condition data and for foveal vision, afirst optical power based on the prescription of the wearer and at leastone optical element of the at least three optical elements has anoptical function of not focusing an image on the retina of the eye forperipheral vision.
 14. The method according to claim 13, wherein duringthe determining at least 50% of the at least three optical elements aredetermined to focus an image at a given distance of the retina.
 15. Themethod according to claim 13, further comprising: obtaining frontsurface data representative of a front surface of the lens element,wherein, during the determining, a shape of a back surface and the atleast three optical elements to be placed on the front surface aredetermined so that the prescription portion provides, in wearingconditions corresponding to the wearing condition data and for fovealvision, the first optical power based on the prescription of the wearerand the at least one optical element of the at least three opticalelements has the optical function of not focusing the image on theretina of the eye for peripheral vision.